With this factory, we want to construct ourselves the TLS dialer so that we can use a dialer wrapper that always sets timeouts when reading, addressing https://github.com/ooni/probe/issues/1609. As a result, we cannot immediately replace the i/e/netx factory for creating a new HTTP transport, since the functions signatures are not directly compatible. Refactoring is part of https://github.com/ooni/probe/issues/1505.